T-ALL Cases Research Articles

Survival and prognostic factors for relapsed childhood acute lymphoblastic leukemia after treatment with the Chinese children's cancer group ALL-2015 protocol: a single center results.

This retrospective study was conducted to assess the survival rates and prognostic factors in children with relapsed acute lymphoblastic leukemia (ALL) who were treated according to the Chinese Children's Cancer Group ALL-2015 protocol at the Children's Hospital of Chongqing Medical University. The study cohort involving 852 evaluable children with ALL reported a total of 146 relapses during a median follow-up period of 53 months. The primary outcomes measured were the second complete remission (CR2) rates, and 5-year event-free survival (EFS) and overall survival (OS) for patients who received re-treatment post-relapse. Patient data were stratified by ALL subtype (B-ALL vs. T-ALL), age at relapse, site of relapse, and timing of relapse. Univariate and multivariate analyses were performed to identify factors significantly associated with EFS and OS. As of March 31, 2023, 146 relapses were observed, including 128 B-ALL and 18 T-ALL cases. The 8-year CIR was (19.8 ± 1.6)%, with no significant difference between B-ALL and T-ALL (P=0.271). Among the 105 patients who underwent re-treatment, 70 achieved CR2, resulting in a CR2 rate of 67.6%. The 5-year EFS and OS rates for re-treated patients were (45.0 ± 5.4)% and (56.9 ± 5.2)%, respectively. Significant differences in 5-year OS and EFS were found between B-ALL and T-ALL relapses (P < 0.001). The 5-year EFS and OS varied significantly with relapse timing and site of relapse. Factors significantly affecting EFS after relapse included the site of relapse, immunophenotyping, CR2 achievement, and hematopoietic stem cell transplantation (HSCT). Immunophenotyping, CR2 achievement, and HSCT were also identified as significant factors affecting OS after relapse. Despite treatment with the CCCG-ALL-2015 protocol, a significant relapse rate was observed, with 72% of children opting for re-treatment post-relapse. The study highlights the importance of considering specific prognostic factors to inform tailored treatment strategies for relapsed childhood ALL. The findings emphasize the need for further research into improving therapeutic approaches for this patient population. This retrospective study was conducted to assess the survival rates and prognostic factors in children with relapsed acute lymphoblastic leukemia (ALL) who were treated according to the Chinese Children's Cancer Group ALL-2015 protocol at the Children's Hospital of Chongqing Medical University.

The immunophenotypic and clinicohematological characteristics of T-ALL cases detected over a three-year period in a tertiary institution

The immunophenotypic and clinicohematological characteristics of T-ALL cases detected over a three-year period in a tertiary institution

Clinicopathological differences between T-lymphoblastic leukemia/lymphoma, early T-precursor lymphoblastic leukemia/lymphoma, and mixed-phenotype acute leukemia with T lineage: An analysis of 41 adult cases

The histopathological diagnosis of T-lymphoblastic leukemia/lymphoma, NOS (T-ALL), is based on morphology and positivity for CD3 and TdT. Early T-precursor lymphoblastic leukemia/lymphoma (ETP-ALL) and mixed-phenotype acute leukemia (MPAL), T/M, and/or B rarely occur and are usually diagnosed using flow cytometry. Using only formalin-fixed paraffin-embedded tissue raises the risk of misdiagnosis due to underestimation. Immunostaining markers for T cell (CD1a, CD4, CD5, CD8), B cell (CD19, CD10, CD22, CD79a), and stem/myeloid-related cell (CD33, CD34, CD117, MPO, lysozyme) diagnosed 25 T-ALL cases (61%), 7 MPAL (17%), 6 ETP-ALL (15%), and 3 near ETP-ALL (7%), with subsequent analysis of their clinicopathological characteristics. Patients with MPAL had significantly poorer 2-year progression-free survival (14.3% vs. 60.4%, P = 0.012) and 5-year overall survival (28.6% vs. 65.9%, P = 0.011) than did those with T-ALL, whereas ETP-ALL and near ETP-ALL did not. Of the seven patients with MPAL, three were classified as T/B, two as T/M, and two as T/M/B. Because most MPALs (6/7) share the ETP-ALL phenotype, immunohistochemistry for CD19 and MPO should be performed to avoid misdiagnosing MPAL as ETP-ALL. All three patients with TdT-negative MPAL died of the disease. Four patients with MPO-positive MPAL relapsed during the early phase (1–9 months). Five patients received the ALL regimen, but two patients received acute myeloid leukemia and lymphoma regimens, respectively. In this study, MPAL exhibited a poorer prognosis compared to T-ALL, unlike ETP-ALL. Thus, immunohistochemical classification with multiple antibody panels is useful for accurate diagnosis and treatment.

THE SIGNIFICANCE OF MINIMAL RESIDUAL DISEASE IN ACUTE LYMPHOBLASTIC LEUKAEMIA: A SINGLE CENTRE STUDY

In Acute lymphoblastic Leukemia (ALL) assessment of molecular response to treatment, assessing minimal residual disease (MRD) is a major independent predictor of treatment outcome. Consequently, MRD is implemented in all ALL-treatment protocols to fill up or to redefine stratification of multifactorial risk with optional intensity of customized treatment. Aim: to specify the significance of MRD in the assessment of remission in children with ALL with results discordant between morphology and flow cytometry at the end of induction phase of therapy. Materials and Methods: A descriptive cross-sectional study was conducted at Jin Oncology Center from March 2019 through November 2023. Data were taken out of the records of 58 patients who had ALL less than 16 years old. All patients were less than 16 years old and treated by ukall. They were diagnosed using peripheral blood morphology, bone marrow study and/or flow cytometry when lymphoblasts in peripheral blood or bone marrow aspirate are ≥20% and was confirmed by flow cytometry. On 29th day of induction therapy, bone marrow was examined for morphology and flow cytometry. The presence or absence of MRD was determined, and CD19, CD10 and tdt were tested. By morphologic assessment they were divided patients into: Category 1, C1 (&lt;5% blasts), Category 2, C2 (5-20% blasts), and Category 3, C3 (&gt;20% blasts). Statistical analysis was made using SPSS version 25. P value of less than 0.05 was considered significant. Results: The study involved 58 patients who had ALL. with a median age of 6.5 years, male to females ratio of 1.76:1, mean platelet count of 96.6 x 10⁹/L ,mean hemoglobin of 8.6 g/dL, mean leucocyte count of 74.3 x 10⁹/L), 48 cases (82.7%) of B-cell lineage and 10 cases (17.3%) of T-cell lineage, 94.6% of the B-cell cases were of the common B-ALL and the rest Pro-BALL type, 54.6% of the T-cell ALL was cortical T-ALL and 44.4% Early T-cell ALL. They were tested for MRD by morphology and flow cytometry on day 29. By morphology, 46 patients had remission but by flow only 24 cases. Seventeen cases had residual blasts &gt;5%. In 19 cases there was a discrepancy between the results of morphology and flow. Twenty-five cases (52.08% of B-cell cases) were positive for MRD by flow results. Eight of the ten cases of T-ALL (80%), were positive for MRD by flow cytometry. Among 48 cases of B-ALL, 36 were in C1 category (morphologically in remission), 11 cases were in C2 category and one case in the C3 category. Of cases in C1 category, 17 were MRD +ve and 19 were MRD –ve by flow cytometry. In the C2 category, only 2 out of the 11 cases (18.18%) had discordant results between morphology and flow results. The correlation between morphology and flow results was 100% in the C3 category. Conclusion: MRD should not be the surrogate of morphology but to be used in conjunction in order to give us a more accurate representation of status of remission.

Targeting the TNF/IAP pathway synergizes with anti-CD3 immunotherapy in T-cell acute lymphoblastic leukemia

AbstractT-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy. Current treatments, based on intensive chemotherapy regimens provide overall survival rates of ∼85% in children and <50% in adults, calling the search of new therapeutic options. We previously reported that targeting the T-cell receptor (TCR) in T-ALL with anti-CD3 (αCD3) monoclonal antibodies (mAbs) enforces a molecular program akin to thymic negative selection, a major developmental checkpoint in normal T-cell development; induces leukemic cell death; and impairs leukemia progression to ultimately improve host survival. However, αCD3 monotherapy resulted in relapse. To find out actionable targets able to re-enforce leukemic cells’ vulnerability to αCD3 mAbs, including the clinically relevant teplizumab, we identified the molecular program induced by αCD3 mAbs in patient-derived xenografts derived from T-ALL cases. Using large-scale transcriptomic analysis, we found prominent expression of tumor necrosis factor α (TNFα), lymphotoxin α (LTα), and multiple components of the “TNFα via NF-κB signaling” pathway in anti-CD3–treated T-ALL. We show in vivo that etanercept, a sink for TNFα/LTα, enhances αCD3 antileukemic properties, indicating that TNF/TNF receptor (TNFR) survival pathways interferes with TCR-induced leukemic cell death. However, suppression of TNF-mediated survival and switch to TNFR-mediated cell death through inhibition of cellular inhibitor of apoptosis protein-1/2 (cIAP1/2) with the second mitochondrial-derived activator of caspases (SMAC) mimetic birinapant synergizes with αCD3 to impair leukemia expansion in a receptor-interacting serine/threonine-protein kinase 1–dependent manner and improve mice survival. Thus, our results advocate the use of either TNFα/LTα inhibitors, or birinapant/other SMAC mimetics to improve anti-CD3 immunotherapy in T-ALL.

JAK2 Kinase Fusion and Myeloid Involvement in Acute Lymphoblastic Leukemia

Introduction JAK2 fusion genes (FGs) are rare but can be found in various phenotypes of myeloid or lymphoid malignancies. Both in the 5th edition of the World Health Organization Classification of Haematolymphoid Tumors (WHO-HAEM5, PMID: 35732831) and the International Consensus Classification (ICC, PMID: 35767897), JAK2-FGs were included in the diagnostic entity of myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (MLN-TK or MLN-eo), and both suggest MLN-TK/eo as a priority diagnostic entity. It is highlighted in ICC that cases presenting as acute lymphoblastic leukemia (ALL) with M/LN-eo differ from de novo B-ALL and T-ALL in the involvement of myeloid cells. There is still a lack of research reports about how many JAK2-FG-positive ALL cases developed from M/LN-eo or had myeloid involvement. Methods A total of 21 ALL cases (Table 1) were enrolled in this study. The positive for JAK2-FGs were determined by G-banding karyotype analysis, transcriptome sequencing (RNA-seq; PMID: 34135310), reverse transcription PCR (RT-PCR), and interphase fluorescence in situ hybridization (I-FISH) with the JAK2 break-apart probe. Gene mutation analysis (PMID: 29932212) was also performed. According to whether there were FISH-JAK2 split signals in rod and lobed nuclear cells (Figure 1A), the cases were divided into My+ group (with myeloid involved) and My- group (without myeloid involved), respectively. Results Among these cases, there were 14 males and 7 females (M:F = 2:1); 15 B-ALL and 6 T-ALL cases; the median age was 22 years old (range 5-55). All cases were positive for JAK2-FGs in RNA-seq analysis, and all FGs were verified by RT-PCR and Sanger sequencing. A total of 16 JAK2 partner genes were detected (Table 1, Figure 1B/C), of which FNBP1, CDK5RAP2, GTF2I, and C14orf 93 have not been reported previously. All cases retained the complete kinase domain of the JAK2 gene, and 13 cases retained part or all of the JAK2 pseudo-kinase domain in their JAK2-FGs. Karyotype abnormalities were detected in 17 cases (81%), with 9p24 involved in 10 cases (48%), abnormalities other than 9p24 were observed in 7 cases, and karyotype was normal in 4 patients. FISH-JAK2 inspection showed split signals in 20 cases and showed negative results in case #21 who with a complex karyotype abnormality. Twelve cases (12/20=60%) showed JAK2 split signals in rotundum, rod, and lobed nuclei (Table 1, My+ group), suggesting both lymphoid and myeloid lineages were involved. We further investigated samples of 4 cases at the time of morphological complete remission after induction chemotherapy, of which the immunophenotype analysis was also negative for lymphoid blast cells. FISH-JAK2 inspection showed split signals accounting for 13%~79% of the nucleus, with split signals in the rod/lobed nucleus, and RT-PCR also confirmed abundant JAK2-FG transcripts in these samples. There were 8 B-ALL and 4 T-ALL cases in the My+ group, of which 2 T-ALL cases were also positive for STIL::TAL1 fusion, and 3 cases experienced eosinophilia during the course of the disease (Table 1). The 5 cases whose JAK2 partner genes were lymphoid development-related transcription factors (ETV6, PAX5) were all in the My- group. All My- cases and #21 had no documented eosinophilia. Among the 21 cases in this cohort, 13 had white blood cell (WBC) counts &amp;gt;50×10 9/L at diagnosis, and no significant hepatosplenomegaly. The total follow-up time was 2-89m, with a median overall survival (OS) time of 17m. Fourteen cases underwent allo-HSCT, and the median OS was 29.5m in the HSCT group and 9m in the non-HSCT group, respectively. The median OS was 15.5m in the My+ group and 29m in the My- group. The leukemia cells in these cases are prone to be in a high and rapid proliferation state, and they generally have a short OS and dismal prognosis. Conclusions Myeloid involvement accounted for 60% of JAK2-FG positive ALL and My+ cases had a worse prognosis and shorter OS than My- cases in this study. I-FISH inspection can be used as a method to determine whether there was myeloid involvement and provide valuable information for accurate analysis. The incidence of JAK2-FGs is low in ALL, but the fusion partners are diverse. This group of cases is more likely to have cryptic JAK2 translocations and with dismal prognosis. The phenotype of JAK2-FG malignancies is jointly determined by multiple factors under the influence of partner genes, accompanying fusion genes, and accompanying mutations.

Project Evolve, Evaluation of Lineage Switch (LS), an International Initiative: Preliminary Results Reveal Dismal Outcomes in Patients with LS

Introduction: Lineage switch (LS) refers to the transformation of acute leukemia from one cell lineage to another (e.g., lymphoid (ALL) to myeloid (AML)). This rare phenomenon, distinct from treatment induced malignancy (i.e., t-AML) and mixed phenotype acute leukemia (MPAL), is increasingly being observed following cell surface antigen targeting. Given challenges in the diagnosis and treatment of LS, Project EVOLVE was developed to globally identify cases of LS following immunotherapy. Methods: A protocol and data collection form for this IRB exempt study was widely disseminated to capture deidentified LS case information across multiple centers and cancer consortia. This included collection of data from published reports of LS, with authors contacted to obtain additional information. For this analysis, LS was defined by the emergence of cell-surface markers warranting reclassification of the original leukemia as a different lineage derivation based on the immunophenotype, including cases of AML emerging alongside the original ALL. “Confirmed” LS cases included those where retention of original cytogenetic or molecular aberrations and/or the clonal immunoglobulin rearrangement patterns were verified to confirm the clonal relationship. “Suspected” LS cases included those where samples to confirm clonality marker retention could not be obtained, but the clinical presentation was consistent with LS. The term “transition” was applied when immunophenotypic shifts were transient. Cases with new cytogenetic abnormalities unrelated to the original diagnosis and compatible with t-AML were excluded. Statistical analysis was primarily descriptive. Data cut-off was July 26, 2023. Results: A total of 58 cases were identified, including 19 cases referenced in prior publications. Of the 58, 11 cases were excluded from this initial analysis, including: 4 cases of t-AML, 2 cases of T-ALL to AML, and 5 “transition” cases. Collectively, 47 cases of LS (43 “confirmed”; 4 “suspected”), spanning across 3 continents and 8 countries, were analyzed. (Fig. 1A) Cases included transition from B-ALL to AML in 36 (76.6%) and to MPAL/biphenotypic/ambiguous lineage in 11 (23.4%). Two likely had MPAL at diagnosis and a third with chronic myeloid leukemia. The median age at initial diagnosis was 8.4 years (range, 1 day-76.5 years); median age at LS presentation was 11.0 years (range 0.4-77.3 years). Twenty-three (48.9%) were male and 19 (40.4%) had prior stem cell transplant (SCT). Baseline cytogenetics showed KMT2A rearrangement in 27 (57.4%). Baseline myeloid antigen co-expression was seen in 22 of 23 patients with submitted data, but variation in degree of expression across patients and antigens was substantial. The most proximal immunotherapy prior to development of LS was CAR T-cells in 23 (48.9%) and blinatumomab in 24 (51.1%). The median time from the most proximal immunotherapy to development of LS was 1.6 months (range, 7 days-36.5 months). In 7 (29.2%) patients receiving blinatumomab, LS developed during the infusion. LS presented as isolated marrow relapse in 27 (57.4%), isolated CNS in 2 (4.3%), isolated non-CNS extramedullary disease in 3 (6.4%), combined relapse in 14 (29.8%) and unreported in 1. First line treatment for LS was chemotherapy induction in 31 (66.0%), palliative care/no therapy in 8 (17.0%), and alternative therapies in the remaining 8 (17.0%). In 35 (74.5%) patients, remission induction was the goal of first line therapy. Fifteen (31.9%) achieved a complete remission (CR) of whom 2 were treated with palliative intent. Across all patients, 8 (17.0%) are alive in remission, the longest being 4.7 years from LS diagnosis; 2 (4.3%) are alive with active LS and 37 (78.7%) died from LS, their original disease, or complications of treatment of LS (Fig 1B). For those alive in CR (n=8), 7 (87.5%) proceeded to a consolidative SCT for treatment of LS and 1 patient, an octogenarian remains in remission after AML directed therapy. Conclusions: LS is emerging as an important mechanism of immune escape following immunotherapy. Project EVOLVE provides the largest dataset of patients with LS to date. This systematic, international effort reveals substantial complexity and variability in diagnosing and managing LS. Unfortunately, outcomes following LS are grim, underscoring the critical need to identify risk factors of and optimal therapies for this leukemia transformation.

Prognostic Features of CD9 in Childhood Acute Lymphoblastic Leukemia - a Retrospective Analysis of a Nation-Wide Multicenter Study in China

Background and objectives: The outcomes of children with acute lymphoblastic leukemia (ALL) have been incrementally improved with risk-directed chemotherapy but therapy responses remain heterogeneous in clinically defined risk groups. Parameters with added prognostic values are therefore warranted to refine the current risk stratification system and inform appropriate management. CD9, a cell surface protein presented on malignant lymphoblasts, may have such predictive characteristics as shown by our previous single-center study conducted in Hong Kong (Leung et al, Leukemia, 2020). This study aims to determine the precise prognostic features of CD9 in a nation-wide, multicenter childhood ALL cohort in China, and deliver algorithms for identification of patients who may benefit from early interventions. Study design and outcome measures: This multicenter cohort study included childhood ALL patients (aged &amp;lt;18 years) enrolled into the Chinese Children Cancer Group (CCCG)-ALL-2015 study from January 2015 to December 2019, with 7,640 patients from 20 tertiary hospitals in China treated with a uniform protocol. A total of 3,781 subjects (49.5%) from 16 sites had flow cytometry data on lymphoblast CD9 at diagnosis. The final study cohort comprised 3,395 B-ALL and 386 T-ALL patients with a median follow-up of 53.9 months. The primary outcomes were 5-year overall survival (OS), event-free survival (EFS), and cumulative incidence of relapse (CIR) for patients with CD9 + or CD9 - phenotypes (positivity defined by the presence of ≥20% CD9 + blasts evaluated through a univariate analysis demonstrating the highest odds for adverse events or relapse at this cut-off). The secondary outcomes were 5-year OS, EFS, and CIR rates of CD9 + and CD9 - patients after inclusion of known prognostic factors, including risk assignment, cytogenetic anomalies, and minimal residual disease (MRD) status. Survival benefits of CD9 + subjects from treatment intensification or hematopoietic stem cell transplantation (HSCT) were analyzed. Results: CD9 was expressed in 88.5% of B-ALL and 27.9% of T-ALL cases. It conferred a dismal EFS (82.1% vs. 89.3%, P=0.001) and a higher CIR (15.5% vs. 7.8%, P&amp;lt;0.001) in B-ALL but not T-ALL patients. The prognostic impact of CD9 is much more prominent in subjects with adverse presenting features or poor early treatment responses, as best exemplified in those assigned to the intermediate/high-risk arms (EFS: 72.8% vs. 83.2%, P=0.028; CIR: 23.1% vs. 10.2%, P=0.003) or those with positive MRD at day 19 (EFS: 65.2% vs. 82.0%, P=0.053; CIR: 30.3% vs. 9.7%, P=0.007). The adverse impact of CD9 is confined to specific cytogenetics, including BCR-ABL1 (CIR: 39.5% vs. 0%, P=0.019) and normal karyotype (CIR: 15.0% vs. 6.8%, P=0.034). In multivariate analyses, CD9 remains an independent factor predicting event-free survival (HR=1.917, P=0.001) and relapse (HR=2.208, P&amp;lt;0.001). The time to and site of relapse did not differ between CD9 + and CD9 - patients. For CD9 + patients with MRD at the end of induction, treatment upstaging only benefited initial low-risk subjects. HSCT at first remission did not improve the outcomes of high-risk subjects with a CD9 + phenotype. Conclusions: This is the largest study to evaluate the significance of CD9 in childhood ALL. We confirmed the results of our previous single-center study with this multicenter national study. CD9 positivity is definitively associated with a higher relapse probability particularly for patients with intermediate/high risk diseases, MRD positivity or specific cytogenetic background. BCR-ABL1 + patients with a CD9 - phenotype had excellent outcomes and HSCT may not be required. Whereas MRD + patients who were CD9 + had poor outcomes, and therefore should have early interventions with innovative treatments to reduce the risk of relapse. With these, we propose to incorporate CD9 into the diagnostic immunophenotyping panel to inform risk stratification and management of childhood ALL.

Fratricide-Resistant Anti-CD2 Chimeric Antigen Receptor T-Cells with Endogenous CD2 Knockout Are Highly Effective Against T-Cell Neoplasms

T cell neoplasms, such as peripheral T cell lymphomas (PTCL) and acute T cell lymphoblastic leukemia (T-ALL), have some of the worst prognoses of all hematological malignancies. Poor outcomes are driven by a limited number of effective treatments, particularly in relapsed and refractory settings. While chimeric antigen receptor T cell (CAR-T) immunotherapy has been successful in other hematological diseases, its clinical use against T cell neoplasms is limited due to a lack of unique tumor-specific antigens. Additionally, CAR specificity against pan-T cell antigens causes CAR-T fratricide and insufficient manufacturability for therapeutic dosing. Early studies of CAR-T against CD5- and CD7-expressing T cell neoplasms have shown responses, however, 1) most patients ultimately relapse, and 2) in some patients, antigen negative relapse has occurred. To circumvent these obstacles, we hypothesized that targeting CD2, a pan-T cell antigen, using anti-CD2 CAR-T cells that are engineered to lack CD2, would permit effective CAR-T manufacturing against T cell neoplasms. In a retrospective analysis of clinical flow cytometry diagnostic samples, we found CD2 expression in 25 of 33 (75.8%) and 37 of 51 (72.5%) pediatric PTCL and T-ALL cases, respectively. Similarly, we found 82 of 89 (92.1%) adult PTCL cases with CD2 immunohistochemical expression, which exceeded CD7 expression (38 of 90, 42.2%) that is currently being evaluated in early phase clinical trials. We optimized early CD2 knockout (KO) during CAR-T cell manufacturing from human donor T cells (KO efficiency: 81.2% ± 2.4, n=9 donors). We next engineered a best-in-class, 4-1BB-costimulated, second-generation CD2KO anti-CD2 CAR-T product (CART2) via lentiviral transduction ( PANEL A) using seven distinct single-chain variable fragments (transduction efficiency: 60.2% ± 5.5, n=7 donors) based on cellular expansion and stressed in vivo efficacy against CD2+ T-ALL cells (Jurkat). There were no significant differences in population doublings during CART2 expansion as compared to both CD2 wild-type (CD2 WT) untransduced T cells (Mock UTD) and CD2KO untransduced T cells (CD2KO UTD) (6.20 ± 0.42 vs. 6.12 ± 0.62 vs. 6.67 ± 0.68, respectively, Day 15, n=3 donors), while CD2 WT CART2 cells failed to expand due to fratricide. CART2 cells had no significant differences in T cell memory phenotypes or T cell exhaustion markers, including PD1 and LAG3 expression, at the end of the expansion. Expanded CART2 cells eradicated primary patient-derived CD2+ Sezary cells and CD2+ T-ALL leukemic blasts as measured by in vitro cytotoxicity assays. Cytotoxicity correlated with CD8+ CART2 cells expressing IL-2 (20.4% vs. 0.2% vs. 0.35%), TNFα (28.5% vs. 0.27% vs. 0.2%), and IFNγ (11.27% vs. 0.18% vs. 0.14%) relative to Mock UTD and CD2KO UTD controls stimulated with CD2+ Jurkat cells (n=2 donors). Importantly, we also found both CD2KO UTD and CART2 cells were capable of TNFα and IFNγ release upon interaction with cytomegalovirus and influenza peptides, suggesting that T cells with CD2 perturbations are still able to mediate effector T cell responses. We further demonstrated that CART2 cells were highly effective in controlling systemic tumor burden of T-ALL patient-derived xenograft mouse (PDX) models and significantly improved median overall survival as compared to Mock UTD and CD2KO UTD controls (138 days vs. 30 days vs. 30 days, p=0.0007, Mantel-Cox) ( PANEL B). Long-term tumor control was proportional to CART2 peripheral blood persistence at Day 28 (CD2KO UTD: 186.6 ± 83.7, n=5 vs. CART2: 936.3 ± 241.7, n=5) and Day 100 (CD2KO UTD: N/A vs. CART2: 514.0 ± 441, n=3). We also found that rescue infusion of CART2 could eliminate relapsed T-ALL in PDX mice previously in a remission after initial treatment with anti-CD5 CAR-T cells, with long-term persistence of CD2-negative T cells thereafter. In conclusion, our data demonstrate that CART2 are manufacturable and highly efficacious against T-cell neoplasms. To our knowledge, this is the first report of prolonged efficacy using a CD2-targeted cellular monotherapy in human leukemia preclinical models. This product could be delivered alone or in combination with additional CARs for dual targeting, such as anti-CD5 or anti-CD7 CARs, to reduce the potential of antigen-negative escape. Further research is ongoing to study the effect of CD2 deletion in anti-CD19 CAR T cells and the possible implication for clinical translation.

Novel Orally Available Degrader to Target Lck in T-Cell Acute Lymphoblastic Leukemia

Background T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive blood cancer that develops from abnormal growth of immature T-cell progenitors and constitutes about 15% of all pediatric ALL cases. Despite an overall survival rate of 80% in pediatric T-ALL patients, 20% of patients eventually experience relapse or succumb to refractory disease. Therefore, novel therapies for refractory/relapsed T-ALL patients are urgently needed, and they are currently being developed in clinical and preclinical studies. Based on recent literature, the over-activation of preTCR-LCK signaling has been revealed as a highly effective therapeutic target in T-ALL, with LCK being identified as a therapeutic vulnerability in ~44% of T-ALL cases. The LCK inhibitor, dasatinib, exhibited an anti-leukemia effect in a subset of T-ALL cases but was transient in most cases. Therefore, the development of new agents capable of sustaining inhibition of LCK signaling is needed. Method To validate the effects of the LCK degrader UBX-363, both in vitro and in vivo tests were conducted using dasatinib-sensitive HSB-2 cells (which have higher LCK activity compared to other T-ALL cell lines) and dasatinib-insensitive CCRF-CEM cells. UBX-363 is designed to target LCK through ubiquitin-proteasome system-mediated degradation. Cell proliferation was assessed using detection methods such as the CellTiter-Glo assay, and the degradation activity of the LCK protein in the tested cell lines was evaluated by immunoblotting. To examine the in vivo antitumor effects of UBX-363 or dasatinib, we performed HSB-2 and CCRF-CEM xenograft murine models. CB17/SCID mice were subcutaneously inoculated with 1x10 7 HSB-2 and 5x10 6 CCRF-CEM cells. UBX-363 was orally administered at doses of 0.2, 1, or 5 mg/kg (for HSB-2) and 2.5, 5, or 10 mg/kg (for CCRF-CEM), while dasatinib was orally administered at doses of 5 mg/kg (for HBS-2) and 10 mg/kg (for CCRF-CEM) once daily for 12 days. Results UBX-363 showed superior degradation activity against LCK proteins in the subnanomolar or single-digit nanomolar range of half-maximal degradation concentration in HSB-2 and CCRF-CEM cell lines (0.478 nM and 1.502 nM, respectively). In comparison to the LCK inhibitors dasatinib (~0.307 nM) and saracatinib (~17.41 nM), UBX-363 (~0.121 nM) demonstrated slightly superior anti-proliferative efficacy in HSB-2 cells. In CCRF-CEM cells, UBX-363 exhibited prominent anti-proliferative activity at lower treatment concentrations compared to the other LCK inhibitors (UBX-363: 11.12 nM, dasatinib: 3483 nM, saracatinib: 4383 nM). Furthermore, UBX-363 demonstrated faster tumor regression than dasatinib in the HSB-2 xenograft models. In the CCRF-CEM xenograft model, UBX-363 effectively suppressed tumor growth in a dose-dependent manner, whereas dasatinib showed no inhibitory effect on tumor growth. After 12 days of UBX-363 dosing on CCRF-CEM xenograft mice, the levels of LCK protein in tumor tissue significantly reduced. The degradation activity of UBX-363 on LCK showed about 100% reduction at dosages of 5 mg/kg and 10 mg/kg on day 12. Conclusion UBX-363 demonstrated strong anti-proliferative and anti-tumor effects, as well as degradation activity of LCK, in both in vitro and in vivo models of T-ALL. These results highlight UBX-363 as a promising therapeutic agent for LCK-activated T-ALL. In the future, we will conduct additional research to explore the advantages of this degrader, such as its ability to disrupt scaffolding of LCK, over LCK small molecule inhibitors.

Topological-insulator nanocylinders

Nanostructures, such a quantum dots or nanoparticles, made of three-dimensional topological insulators (3DTIs) have been recently attracting increasing interest, especially for their optical properties. In this paper we calculate the energy spectrum, the surface states and the dipole matrix elements for optical transitions with in-plane polarization of 3DTI nanocylinders of finite height LL and radius RR. We first derive an effective 2D Hamiltonian by exploiting the cylindrical symmetry of the problem. We develop two approaches: the first one is an exact numerical tight-binding model obtained by discretising the Hamiltonian. The second one, which allows us to obtain analytical results, is an approximated model based on a large-RR expansion and on an effective boundary condition to account for the finite height of the nanocylinder. We find that the agreement between the two models, as far as eigenenergies and eigenfunctions are concerned, is excellent for the lowest absolute value of the longitudinal component of the angular momentum. Finally, we derive analytical expressions for the dipole matrix elements by first considering the lateral surface alone and the bases alone, and then for the whole nanocylinder. In particular, we focus on the two limiting cases of tall and squat nanocylinders. The latter case is compared with the numerical results finding a good agreement.

IL-7 receptor expression is frequent in T-cell acute lymphoblastic leukemia and predicts sensitivity to JAK inhibition

AbstractT-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy with a dismal prognosis related to refractory/relapsing diseases, raising the need for new targeted therapies. Activating mutations of interleukin-7–receptor pathway genes (IL-7Rp) play a proven leukemia-supportive role in T-ALL. JAK inhibitors, such as ruxolitinib, have recently demonstrated preclinical efficacy. However, prediction markers for sensitivity to JAK inhibitors are still lacking. Herein, we show that IL-7R (CD127) expression is more frequent (∼70%) than IL-7Rp mutations in T-ALL (∼30%). We compared the so-called nonexpressers (no IL-7R expression/IL-7Rp mutation), expressers (IL7R expression without IL-7Rp mutation), and mutants (IL-7Rp mutations). Integrative multiomics analysis outlined IL-7R deregulation in virtually all T-ALL subtypes, at the epigenetic level in nonexpressers, genetic level in mutants, and posttranscriptional level in expressers. Ex vivo data using primary-derived xenografts support that IL-7Rp is functional whenever the IL-7R is expressed, regardless of the IL-7Rp mutational status. Consequently, ruxolitinib impaired T-ALL survival in both expressers and mutants. Interestingly, we show that expressers displayed ectopic IL-7R expression and IL-7Rp addiction conferring a deeper sensitivity to ruxolitinib. Conversely, mutants were more sensitive to venetoclax than expressers. Overall, the combination of ruxolitinib and venetoclax resulted in synergistic effects in both groups. We illustrate the clinical relevance of this association by reporting the achievement of complete remission in 2 patients with refractory/relapsed T-ALL. This provides proof of concept for translation of this strategy into clinics as a bridge-to-transplantation therapy. IL7R expression can be used as a biomarker for sensitivity to JAK inhibition, thereby expanding the fraction of patients with T-ALL eligible for ruxolitinib up to nearly ∼70% of T-ALL cases.

Abstract 3928: Therapeutic targeting of NOTCH1 and neddylation pathway in T cell acute lymphoblastic leukemia

Abstract T-cell Acute Lymphoblastic Leukemia (T-ALL) is hematologic tumor characterized by the diffuse infiltration of the bone marrow by malignant hematopoietic cells expressing immature T cell markers. Although T-ALL currently has better cure rates primarily due to multiagent or intensified chemotherapy, the prognosis for patients who are resistant or develop relapse to therapy remains very poor. Aberrant Notch homolog-1 (NOTCH1) signaling is a major driver of T-ALL pathogenesis as more than 60% of T-ALL cases harbor activating mutations in the NOTCH1 gene. Gamma Secretase Inhibitors (GSIs) which effectively block the activation of oncogenic protein NOTCH1 are potential candidates for the treatment of T-ALL. However, the clinical application of GSIs is hampered by severe gastrointestinal toxicity due to the inhibition of NOTCH1 signaling in the gut. Here we demonstrate that combination therapy of GSIs and a small molecule inhibitor of the neddylation pathway circumvents the GSI-induced gut toxicity in vitro and in vivo. Genome-wide CRISPR loss-of-function screen in LS174T adenocarcinoma cells revealed neddylation pathway as a main regulator of massive goblet cell differentiation upon NOTCH1 inhibition. Genetic and pharmacologic inhibition of the neddylation pathway in LS174T cells rescued GSI-induced differentiation and cell death. Mechanistically, neddylation inhibition increases the protein stability of Hairy and enhancer of split-1 (HES1), a known regulator of absorptive and secretory cell fate decisions. Combination treatment of GSI and neddylation inhibitor in C57/BL6 mice showed a profound decrease in the number of goblet cells and maintained HES1 protein levels in the intestinal epithelium compared to GSI treatment alone. Remarkably, combined treatment of GSI and neddylation inhibitor in NOTCH1-induced T-ALL mice showed leukemia regression and improved overall survival without any associated gut toxicity. Overall, these results substantiate the potential of targeting NOTCH1 and neddylation pathway in the treatment of NOTCH1-induced T-ALL. Citation Format: Carla Bertulfo, Pablo Perez-Duran, Teresa Palomero, Adolfo Ferrando. Therapeutic targeting of NOTCH1 and neddylation pathway in T cell acute lymphoblastic leukemia. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3928.

Optical Genome Mapping in Routine Cytogenetic Diagnosis of Acute Leukemia

Cytogenetic aberrations are found in 65% of adults and 75% of children with acute leukemia. Specific aberrations are used as markers for the prognostic stratification of patients. The current standard cytogenetic procedure for acute leukemias is karyotyping in combination with FISH and RT-PCR. Optical genome mapping (OGM) is a new technology providing a precise identification of chromosomal abnormalities in a single approach. In our prospective study, the results obtained using OGM and standard techniques were compared in 29 cases of acute myeloid (AML) or lymphoblastic leukemia (ALL). OGM detected 73% (53/73) of abnormalities identified by standard methods. In AML cases, two single clones and three subclones were missed by OGM, but the assignment of patients to cytogenetic risk groups was concordant in all patients. OGM identified additional abnormalities in six cases, including one cryptic structural variant of clinical interest and two subclones. In B-ALL cases, OGM correctly detected all relevant aberrations and revealed additional potentially targetable alterations. In T-ALL cases, OGM characterized a complex karyotype in one case and identified additional abnormalities in two others. In conclusion, OGM is an attractive alternative to current multiple cytogenetic testing in acute leukemia that simplifies the procedure and reduces costs.

Allogeneic hematopoietic stem cell transplantation in acute leukemia patients with the SET-NUP214 fusion gene: Efficacy and survival analysis

Objective: To investigate the clinical efficacy of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for patients with acute leukemia who are positive for the SET-NUP214 fusion gene (SET-NUP214+AL). Methods: This was a retrospective case series study. Clinical data of 18 patients with SET-NUP214+AL who received allo-HSCT in the First Affiliated Hospital of Soochow University and Soochow Hongci Hematology Hospital from December 2014 to October 2021 were retrospectively analyzed to investigate treatment efficacy and prognosis. The Kaplan-Meier method was used for survival analysis. Results: Of the 18 patients, 12 were male and 6 were female, and the median age was 29 years (range, 13-55 years). There were six cases of mixed phenotype acute leukemia (three cases of myeloid/T, two cases of B/T, one case of myeloid/B/T), nine cases of acute lymphoblastic leukemia (ALL) (one case of B-ALL and eight cases of T-ALL), and three cases of acute myeloid leukemia. All patients received induction chemotherapy after diagnosis, and 17 patients achieved complete remission (CR) after chemotherapy. All patients subsequently received allo-HSCT. Pre-transplantation status: 15 patients were in the first CR, 1 patient was in the second CR, 1 was in partial remission, and 1 patient did not reach CR. All patients were successfully implanted with stem cells. The median time of granulocyte and platelet reconstitution was +12 and +13 days, respectively. With a median follow-up of 23 (4-80) months, 15 patients survived, while 3 patients died. The cause of death was recurrence of SET-NUP214+AL after transplantation. After allo-HSCT, 5 patients relapsed. The estimated 3-year overall survival (OS) and relapse-free survival (RFS) rates were 83.3%±15.2% and 55.4%±20.7%, respectively. Among the 15 patients who achieved CR before transplantation, there was no significant difference in OS and RFS between haploidentical HSCT and matched sibling donor HSCT (all P>0.05). Conclusions: Allo-HSCT can improve the prognosis and long-term survival rate of patients with SET-NUP214+AL. Disease recurrence is the most important factor affecting long-term survival.

Clinicopathologic characteristics, genetic features, and treatment options for acute lymphoblastic leukemia with JAK2 rearrangement—A 10-case study and literature review

JAK2 rearrangement (JAK2-R) in acute lymphoblastic leukemia (ALL) is rare and often categorized as B-ALL with BCR::ABL1-like features based on the World Health Organization classification. We report 10 patients with JAK2-R ALL, 9 males and 1 female, with a median age 40.5 years. Eight patients presented with marked leukocytosis (median WBC, 63 × 10 9/L) and hypercellular (>95%) bone marrow with increased lymphoblasts (72%-95%). There was no evidence of bone marrow fibrosis or hypereosinophilia. Immunophenotypic analysis showed 9 B-cell and 1 T-cell neoplasms. Using fluorescence in situ hybridization (FISH) and RNA sequencing analysis, JAK2 partners were identified for 7 cases and included PCM1 (n=4), ETV6 (n=2) and BCR (n=1). All patients received upfront polychemotherapy. Additionally, 2 patients received ruxolitinib, 2 received allogeneic stem cell transplant, and 1 received CAR-T therapy. The 1- and 3-year overall survival rates were 55.6% and 22.2%, respectively. A literature review identified 24 B-ALL and 4 T-ALL cases with JAK2-R reported, including 16 males, 6 females and 6 gender not stated. Many JAK2 partner-genes were reported with the most common being PAX5 (n=7), ETV6 (n=4), BCR (n=3) and PCM1 (n=2). Survival data or 13 reported cases showed 1- and 3-year overall survival rates of 41.7% and 41.7%, respectively. In summary, JAK2-R ALL occurs more often in adult males, are mostly of B-cell lineage, and associated with an aggressive clinical course. Absence of eosinophilia and bone marrow fibrosis and no evidence of preexisting/concurrent JAK2-R myeloid neoplasms distinguish JAK2-R ALL from other myeloid/lymphoid neoplasms with eosinophilia and JAK2-R.

Global DNA Methylation Levels in Epstein-Barr-Virus-Positive Iraqi Patients with Acute Lymphoblastic Leukaemia

Acute lymphoblastic leukemia (ALL) is one of the commonest hematological malignancies affecting children and adults. Recent evidence suggests an involvement of Epstein-Barr virus (EBV) in ALL pathogenicity. Epigenetic aberration, especially altered DNA methylation marks, is a key event of cancer development. The present study aims to investigate how the ALL epimethylome reacts to viral infection through the assessment of the total 5-methylcytosine (5mC) levels in ALL patients, according to EBV infection. The 5mC global DNA methylation levels in 50 diagnosed ALL patients (age mean 26.23 yrs; age range 10-60 yrs) and 25 age-matched healthy controls were assessed using MethylFlash™ Methylated DNA Quantification Kit. Acute primary EBV infection in the studied subjects was detected by measuring Epstein-Barr Virus (EBNA-1) IgG levels using ELISA. The results showed a significant (P˂0.001) decrease in 5mC levels in ALL-EBV positive cases as compared to those who were negative for EBV infection (0.234±0.117 vs. 0.441±0.153, respectively). The reduction in the average 5mC level seemed to be negatively correlated with EBV viral load (r = -0.599, p= 0.001). Additionally, 5mC levels were able to distinguish between ALL main subtypes (B-ALL and T-ALL; derived from B or T lymphocytes), where T-ALL cases showed significantly (P=0.005) higher 5mC levels than those of B-ALL cases (0.587±0.070 vs. 0.180±0.092, respectively). Also significantly (P=0.04) lower 5mC levels were detected in Philadelphia chromosome-positive (Ph+) ALL cases than in those who were negative to this genetic abnormality (Ph- -ALL) (0.13±0.021 vs. 0.179±0.093, respectively). Overall, the findings of the present study suggest an involvement of EBV infection in ALL pathogenicity, with the potential of utilizing the differences in global DNA methylation levels in ALL patients' risk stratification.

Immunophenotype of Acute Lymphoblastic Leukemia: The Experience of University Hospital Centre Casablanca - Morocco.

Acute lymphoblastic leukemia (ALL) encompasses a group of lymphoid neoplasms that morphologically and immunophenotypically resemble B-lineage and T-lineage precursor cells. Our objective is to describe the immunophenotypic aspects of acute lymphoblastic leukemia (All) diagnosed by flow cytometry at the hematology laboratory of IBN ROCHD University Hospital Center and to compare them with those reported in other series. This is a descriptive study over a period from August 2016 to October 2021, during a 5 year-and-2-month period. Immunophenotyping was performed at the flow cytometry unit on a Beckman-Coulter with 6 colors and 2 lasers in the hematology laboratory of the same hospital and data was collected retrospectively from the patients' files, their medical prescription files, kalisil software, and a data collection form we have established. The 440 patients had ages ranging from 1 month to 76 years, with a median of 9.5 years and the overall male-to-female ratio was 1.44. The immunological subtyping revealed that 82.5% of cases were B-ALL and 17.5% were T-ALL; of these B-ALL cases 230 (63.36%) were children (range: 0.1 - 15 years) and 134 (36.91%) were adults (range: 16 - 76 years); T-ALL were distributed in both age groups, 49 cases (37.7%) were children (range: 2 - 15 years) and 28 (21.56%) were adults (range: 18 - 63 years). All patients presented at least one abnormal blood count; thrombocytopenia has been observed in 89.4% of cases, anemia in 86.5% of cases, hyperleukocytosis in 79.8% of cases, leukopenia in 10.6% of cases, and pancytopenia in 4.8% of cases. The frequency of B-cell markers in B-ALL was found to be 363 (100%) for CD19, 323 (88.94%) for CD10, 290 (80%) for CD79a, and 73 (20%) for CD20. CD34 expression was found in 73 (20%) cases of B-ALL. HLA-DR was found in 54 (15%) cases, while TdT was found in 43 (13%) cases. Aberrant expression of myeloid antigens was found in 94 (26%) cases of B-ALL. Among T-ALL, the positivity of CD3 and CD7 was 100% (77 cases), while CD5 was positive in 58 (75%) cases. CD34 expression was found in only 19 cases of T-ALL. CD4 and CD8 expression was checked in only 9 adult patients and 4 pediatric cases. Out of them, 77.82% of cases were negative for both CD4 and CD8. CD4 and CD8 double positivity was seen in only 11.1% of cases, and 22.4% of cases showed either CD4 or CD8 positivity. We concluded that our study was similar to reports in the Americas and Europe, and it was the first large one that describes the immunophenotypic profile of ALL in the Moroccan population.

Batık Tırnak Tedavisinde Winograde Ve Vandenbos Cerrahi Tekniklerinin Heifetz Evresine Göre Karşılaştırılması

Abstract&#x0D; Background: In ingrown toenail, classifications and the treatment approaches according to staging has been clearly reported in the literature. However, there are not enough data about the selection of the appropriate surgical technique according to the stage. In this study, we compared two different surgical techniques in patients with Heifetz stage 2 and 3 in means of surgical results, recovery time, patient comfort and cosmetics.&#x0D; Methods: Between January 2019 and January 21, patients who applied with the complaint of ingrown toenails who were treated with two mentioned surgical techniques in two centers with at least 1 year follow-up were included. The patients were evaluated preoperatively in means of the Heifetz classification. In group 1 (n:54) matrix excising Winograd and in group 2 (n:51) matrix preserving Vandenbos techniques were used. Postoperative recovery time, complication rates, functional and cosmetic patient satisfaction were evaluated in tall cases. &#x0D; Results: 105 cases of ingrown toenails treated surgically were included in the study. 62 (59%) cases were Heifetz stage 2, 43 (41%) cases were Heifetz stage 3. No statistically significant difference was found between Heifetz stage 2 and stage 3, regardless of surgical technique, in complication, recurrence, patient functional/cosmetic satisfaction rates, and recovery time. In overall analysis regardless of Heifetz staging, recovery time was shorter with Winograd method (p:0.0001), complication and recurrence rates were lower with Vandenbos method (p:0.0001), and VAS cosmetic satisfaction was higher in Vandenbos (p:0.002).&#x0D; Conclusion: Winograd and Vandenbos in Heifitz stages 2 and 3 have low complication rates and high patient satisfaction. Earlier healing could be achieved with the Winograd technique, while low complication/recurrence rates and high cosmetic satisfaction could be achieved with the Vandenbos technique. Early recovery/high cosmetic expectation should be considered instead of Heifetz staging in determining the surgical technique.

CD72 Is a Pan-Tumor Antigen Associated with Childhood Acute Leukemia

Immunotherapy has recently gained increasing attention as a new paradigm shift in cancer and has revolutionized the course of cancer treatment. The identification of ideal tumor-associated antigens (TAA) is a challenging process, since antigens have to be specific for the target cells and assure no off-target effects. We exploited a gene expression dataset of acute leukemias previously generated in our lab to identify potentially interesting TAAs. Among the most interesting hyper- and over-expressed genes with respect to normal bone marrow (BM) and with a surface protein localization, the CD72 was selected because of its specific association with childhood B-cell precursor acute lymphoblastic leukemias (BCP-ALL) and with a large proportion of pediatric acute myeloid leukemias (AML) cases. Based on the findings described below, we here propose CD72 as a novel and robust pan-acute leukemia TAA. Even though CD72 is known to be expressed by B-lineage cells, we profiled its expression in a variety of cell lines and primary samples, providing a map of its expression. CD72 was expressed by BCP-ALL cell lines (NALM-6, SEM, RS-4;11, RHC-ACV) and various AML cell lines (SHI-1, SKNO-1, MV4;11, MOML-13). Conversely, T-ALL cell lines (DND-41, TALL-1, RPMI-8402, ALL-SIL, JURKAT) and non-hematopoietic tumor cell lines (DAOY, NB-1, HT-29, A549, HeLa, MCF7) did not express the antigen. This supports the idea that CD72 is specific for hematopoietic tumors. Furthermore, we tested CD72 expression on major populations within normal BM specimens and on other healthy tissues: skin fibroblasts, mesenchymal stromal cells, skeletal myoblasts, endothelial cells. We confirmed that the antigen is expressed on B-lineage cells, whereas in other cell types we did not detect any signal. Then, to assess the interest of CD72 for the development of chimeric antigen receptor (CAR)-based immunotherapy approaches, we documented that CD72 was not expressed on CD34-positive/CD38-negative hematopoietic stem and progenitor cells (HSPCs) from both mobilized peripheral blood cells and healthy-regenerating BM samples (Figure 1). We profiled CD72 expression by flow-cytometry on 289 pathological pediatric BM samples, including: 93 BCP-ALL at diagnosis and 44 at relapse; 38 T-ALL at diagnosis and 3 at relapse; 68 AML at diagnosis and 12 at relapse; blast cells from 6 myelodysplastic syndromes; 14 non-hematopoietic solid tumors invading BM (4 rhabdomyosarcomas, 6 neuroblastomas, 4 Ewing's sarcomas); blast cells from 3 T-cell Lymphoblastic Lymphomas and 8 B-lineage Non-Hodgkin Lymphomas (NHL) with BM involvement. Data from clinical samples confirmed the in silico and in vitro prediction. CD72 was positive in 134/137 (98%) of the examined BCP-ALL cases and in all B-lineage NHL and 52/80 (65%) of AML cases. Conversely, CD72 was expressed only in 2/44 (4%) of T-ALL cases and was absent in T-cell NHL and in non-hematopoietic solid tumors. Notably, CD72 was expressed by all 12 BCP-ALL patients that were previously treated with CD19-directed immunotherapies, including four patients who lost CD19 expression. Moreover, CD72 was positive on two rare cases of CD19-negative BCP-ALL at diagnosis (Figure 2). Within our AML cohort, we did not detect any difference in CD72 expression across AML genetic subgroups. Taken together, the preliminary data here reported highlight the potential clinical usefulness of CD72 for advanced diagnostics, including the ability to identify blast cells in case of CD19 loss, and provide support for developing novel immunotherapy approach directed at CD72 that may be endowed with the unique potential of targeting both acute lymphoid and myeloid leukemia. Figure 1. CD72 expression by flow-cytometry on healthy CD34+ and CD34+/CD38- cells from healthy-regenerating bone marrow. CD72 expression was evaluated according to AIEOP-BFM Consensus guidelines, comparing the fluorescence shift and distribution pattern of the cells to the appropriate negative control. Figure 2. CD72 expression on CD19-negative BCP-ALL by flow-cytometry at first diagnosis and at time of relapse after CD19-directed immunotherapy. B-lineage was assigned with the contribution of other antigens relevant in immunophenotyping of acute leukemia. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal